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Discussion Starter #1 (Edited)
Here's a another little neat deal for you gear heads out there. In continuing with my non-stock builds, I had some time so I started on a 10 bolt posi upgrading to 12 bolt internals. Neat deal using Tom's axles & 30 spline HT spiders, my clutch kit and some machine work.This would be like Tom's BOE. Now you can get the axles in 17 spline stock setup with snap ring and large flange end but they just aren't going to offer much more then stock. So then next deal would be to retain the stock 10 bolt case, machine it, polish and massage it, add in 30 spline HT spiders, take a set of Tom axles add in my mods, and tune it. You end up with a unit that't stronger then any stock, common rebuilt, new Eaton or Auburn unit. Do have to cut the ears off your carrier(housing) so the axle flanges have room to move.
Pretty trick huh, I just finished the machine and polish work, I'll tune it another day. It will be at the Moroso show on 7/12 and at carlisle if anyone wants to buy it!:thumbsup:


Here is the 12 bolt CS,made to fit the 10 bolt case.




Case Bored for the correct fit.




CS fit


Bored the case for the 30's








Cleaned and Polished case



Same inside- NOTE- I polish these completely inside the case now, this one certainly will work but I would never sell one like that anymore. I would post some pictures of a current one but I can't get onto PB right now.



I'll post some of the final assembly. The next level is a 12 bolt conversion. But that requires a lot more fitting and machine work. This should work nicely in a hot street car. Still pushing it for drag cars with 600+ HP.
 

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Will that setup fit a 82 with a batwing?
 

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If mine ever blows now I know what I need to do. I have a spare housing and case just in case I ever need it.

Good info.
 

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Discussion Starter #5 (Edited)
Will that setup fit a 82 with a batwing?
No you would need to convert to an iron diff. This offers about the best 10 bolt setup for a vette. I wouldn't bother trying to mod the 80-82's. To use an iron unit you will also need the strut rods, brackets, and 1/2 shafts. Adds up fast and the DS needs to be modified.
 

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Discussion Starter #6
Here is a 17 & 30 spline axle comparision





Here is the 17 tooth-30 spline side gear setup for C clip use.



Here are the only clutches I will use, in stock, stock bluprinted or 12 bolt- solid steels,no snowflakes or "fiber coated"
 

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yeah thats what I ment I plan on swapping to a 79 differential anyways

No you would need to convert to an iron diff. This offers about the best 10 bolt setup for a vette. I would bother trying to mod the 80-82's. To use an iron unit you will also need the strut rods, brackets, and 1/2 shafts. Adds up fast and the DS needs to be modified.
 

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OK Gary, I'm game! what ratio are you building it to or are you selling it ready for assembly. Either way, I'm ready to lake you an offer for it and could send you a replacement diff housing and 3 series Posi case if you want replacement cores for your hardware (California rust free and guaranteed to be crack free.) I'm looking for a 4.10 set-up with a steel cap (can send you a replacement Tom's Cap too.) I seem to have less time latley and work is still keeping me busy. Email me at [email protected] even if you sell it as I would like to know how much to convert a Posi case to 12 bolt pinion set-up. I have been thinking about doing this conversion and thinking that if I start to bore a case for larger pinion shaft, I would need to make a fixture as my boring head is a cheap Chinese model (not a Yuasa) and I don't have a long enough boring bar to make a single pass on a case boring job. I can appreciate your fine efforts and know you build a superior quality product, looking forward to talking with you, Thanks, Eric Brandt
 

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Discussion Starter #10
Hi Guys,
Yes this will fit in 79, in fact I believe it came out of a 78 or 79 but the Eaton cases from 69-79 are the same.

Eric,
To be honest I haven't even looked at my cost for all the parts yet or the time I put into this so far. It's something I wanted to do for a while to use a display at local shows and Carlisle. I haven't run one in any of my cars. I have a couple of sets of parts and caught a break in jobs so I set it up and started on it. I hope to finish it by Sat. This is a 3 series case and can use from 273-456 gears,all Tom's gear sets. There was a fellow who contacted me about this a few weeks ago that was interested in it but we haven't been in touch since.

The vette gear set would be 4:11 not that it matters in use compared to a 4:10.

I'll email you as well to answer any question directly.

Interesting thing on the steel caps, not sure if you set up any yet or not but every one I did I had to machine. First parallel grind the cap flat then set it up and bore it 010-020 to setup 001 rock. The 001 rock also can vary a little maybe 001 overall so the parallel gap can be 0005 to 00075"
You have seen my setup in the Bridgeport and that takes me some time to dial it in, tap them in place, then start the cap fit. Some think you use a hand drill and file but that's not how I would do it.


Also on the cases, I've found the factory tolerances all over the place. That's why every one I tune is different. The gear bores can be out 005 from each other,one case was so bad I couldn't tune it at all without a lot of machine work, which just wasn't worth it. The cross shaft holes were probably bored in one pass but that leaves room for deflection using a long bar. I went about it a different way, more time consuming.

:thumbsup:
 

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OK Gary, Email me a price for a completed differential set up with 4.10 gearset but, please look at Mark Williams web site for the 12 bolt ring gears that he sells (stamped ARP MW ENT on them) because I have decided to start running aircraft saftey wire in all my differentials from here on out and the MW bolts are $40 a set which is cheaper than me cussing while trying to drill 10 bolts for saftey wire (and I'm pretty good at that after running a Yamaha TZ 250 road race bike back in the 70's) Big bounus for the Mark Willams bolts is the are about 0.100 shorter than the std ARP ring gear bolts and don't seem to have the problems that ARP designed bolts have (plus putting them in a 10 bolt assembly means you buy 5 sets and get the 6th set for FREE!). It almost seems that Mark Williams has done a few 12 bolts inhis time.:laughing:
 

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Discussion Starter #12
Well I finished this build today in time to bring to the Moroso Vette show in CT & Carlilse next month.
To recap
Vette 10 bolt Eaton case, polished and machined for 12 bolt cross shaft, 30 spline axles,C-Clips, heat treated 10-17 spiders. Axles were treated and ground then fit to 005-008 endplay.
Posi tuned for use without springs. Ready for gears and install.
:thumbsup:

Axles



Assembled,Tuned and ready for axles


Grinding axles faces flat.




I just ground off about 007" because these were sent out to be hardened and only wanted to clean them up.



fitting C clip



Clips are ground to size



I just setup one side for now, once installed in a diff I would final fit to be sure. For demo purposes this is very close.



Done, ready for a ring gear and installation:thumbsup:

 

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Discussion Starter #14 (Edited)
Well to follow up on this build, it ended up in 70 carrier going into a C2 st/strip car. You can see it got the steel cap, 30 spline axles(fit to 005), but what you can't see is the case and new 390 gears were cryro treated for added strength. I don't know if there is a stronger vette 10-bolt out there as this as it all, next step is the full 12-bolt with 1350 axles and then the 12 bolt with 1480's:thumbsup:


 

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That would be going in my car.
Gary, I thank you whole heartedly for your patience with me, and the many options we went over to get to this point, and for all the incidentals that fell in front of you along the way.
I couldn't be happier to deal with someone than you.
I assure you this unit will be tested for its strength.

For the curious, the testbed will be my 64 coupe. My combo is a 355, with about 450 hp, a Coan trans T400, reverse manual valve body, and the 3.90 rear from Gary. I run Firestone Firehawk 245/55/16, and it hooks pretty good.

I had a best of 12.65 before freshening the engine, trans, and now rear diff too.

We'll see what we can do this year with it.
 

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Discussion Starter #18
Ha! Good one, but I can trumph that with the Cryo treatment.

But seriously,as you know the RH side digs into the housing under launch,unlike the LH which pulls out, hence the RH steel cap really isn't needed. I did get a call from someone once though that wanted 2 steel caps fit.
 

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Gary,what are you doing about the problem with egging out of the through pin that holds the spider gears.Mine did that twice.GM housing is too soft.How do you strenghthen it?
 
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